PROJECT SUMMARY/ABSTRACT Higher physical activity (PA) is associated with reduced risk of breast cancer (BC) recurrence and progression and increased survival. Increased PA is also associated with reductions in cardiovascular disease (CVD) mortality, the leading cause of non-cancer mortality among BC survivors (BCS). PA may prevent BC progression and CVD via its effects on inflammation and also decrease CVD risk via effects on cardiometabolic biomarkers. However, the exact biologic mechanisms are poorly understood as few PA interventions include biomarkers of BC progression or CVD risk. Additionally, most PA interventions are costly, intense, on-site multicomponent interventions that provide little insight into what components (i.e. phone calls, Fitbits, etc.) are, or are not, effective, and traditional venous blood sample collection is often costly and requires lab visits limiting the potential public health impact of this research. In order to increase